The present invention relates to an image recording apparatus and image quality control method. More particularly, it concerns an image recording apparatus and image quality control method for obtaining a quality image.
To automatically maintain high quality of an image output of an image recording apparatus, the image must be monitored in some methods not to deteriorate. The methods include the following known techniques.
The Japanese Patent Laid-Open Nos. 63-253383 and 2-93667 disclosed apparatuses that developed a patch pattern and thin lines on a non-image area of a photosensitizer as standard pattern. The standard pattern was read by a photosensor or the like so that the image to be recorded could be monitored. The Japanese Patent Laid-Open No. 62-145266 disclosed an apparatus that developed a standard pattern on an image area of a photosensitizer before transferring the standard pattern to paper. Quality of the image transferred on the paper was monitored by a line density sensor. The Japanese Patent Laid-Open No. 61-1286865 disclosed an apparatus that fixed an image on paper. The image fixed on the paper is measured by a line density sensor.
However, the apparatuses disclosed by the Japanese Patent LaidOpen Nos. 63-253383 and 2-93667 have to develop the patch pattern having different densities and to develop the standard pattern of vertical and horizontal thin lines in addition to the image to be recorded by a user. If the standard pattern is created for every page, toner consumption is greater. If the number of standard patterns created is decreased to every several pages to lessen the toner consumption, then response of control becomes worse. The image quality become unstable. The apparatus disclosed in the Japanese Patent Laid-Open No. 62-145266 has the advantage that the image quality, including characteristics of transference and fixing processes after development, can be stabilized. However, the apparatus has not only the above-mentioned disadvantage, but also the disadvantage that paper is wasted and the printing speed by user is reduced. The apparatus disclosed in the Japanese Patent Laid-Open No. 61-1286865 does not have the above-mentioned disadvantages because the standard pattern is note used. However, the apparatus cannot measure any densities except an average density of the entire output image. The apparatus has lower control capability than the one that can monitor the patch pattern having different densities and the standard pattern of vertical and horizontal thin lines.